Impact of Population Recruitment on the HIV Epidemics and the Effectiveness of HIV Prevention Interventions.

Mechanistic mathematical models are increasingly used to evaluate the effectiveness of different interventions for HIV prevention and to inform public health decisions. By focusing exclusively on the impact of the interventions, the importance of the demographic processes in these studies is often underestimated. In this paper, we use simple deterministic models to assess the effectiveness of pre-exposure prophylaxis in reducing the HIV transmission and to explore the influence of the recruitment mechanisms on the epidemic and effectiveness projections. We employ three commonly used formulas that correspond to constant, proportional and logistic recruitment and compare the dynamical properties of the resulting models. Our analysis exposes substantial differences in the transient and asymptotic behavior of the models which result in 47 % variation in population size and more than 6 percentage points variation in HIV prevalence over 40 years between models using different recruitment mechanisms. We outline the strong influence of recruitment assumptions on the impact of HIV prevention interventions and conclude that detailed demographic data should be used to inform the integration of recruitment processes in the models before HIV prevention is considered.

A review of crustacean sensitivity to high amplitude underwater noise: Data needs for effective risk assessment in relation to UK commercial species.

High amplitude anthropogenic noise is associated with adverse impacts among a variety of organisms but detailed species-specific knowledge is lacking in relation to effects upon crustaceans. Brown crab (Cancer pagurus), European lobster (Homarus gammarus) and Norway lobster (Nephrops norvegicus) together represent the most valuable commercial fishery in the UK (Defra, 2014). Critical evaluation of literature reveals physiological sensitivity to underwater noise among N. norvegicus and closely related crustacean species, including juvenile stages. Current evidence supports physiological sensitivity to local, particle motion effects of sound production in particular. Derivation of correlative relationships between the introduction of high amplitude impulsive noise and crustacean distribution/abundance is hindered by the coarse resolution of available data at the present time. Future priorities for research are identified and argument for enhanced monitoring under current legislative frameworks outlined.

Concurrent training enhances athletes' cardiovascular and cardiorespiratory measures.

We evaluated the effects of concurrent strength and aerobic endurance training on cardiovascular and cardiorespiratory adaptations in college athletes and compared two concurrent exercise (CE) protocols. Separate experiments were performed on 30 women (mean age 19.6 years) and 20 men (20.4 years). In both experiments, subjects were divided into two groups (serial CE and integrated CE) matched for initial physical condition and trained in a vigorous 3-day per week CE program of 9 (men) to 11 (women) weeks. The two CE training protocols were equilibrated for exercise mode, intensity, and volume, differing only in the timing and sequence of exercises. During training, serial CE discernibly (p < 0.05) increased cardiovascular adaptation in women, indicated by reduction (-5.7%) in active heart rate (HR) (HR/aerobic exercise intensity), whereas integrated CE discernibly reduced active HR in women (-10.7%) and men (-9.1%). Before and after comparisons in the larger sample of women showed that serial CE discernibly reduced systolic and diastolic blood pressure (BP) (-8.7% and -14.0%, respectively), increased estimated [latin capital V with dot above]o2max (18.9%), and produced a trend (0.10 > p > 0.05) toward reduced resting HR (-4.9%). Integrated CE in women discernibly reduced systolic and diastolic BP (-13.2% and -12.6%, respectively), increased estimated [latin capital V with dot above]o2max (22.9%), and produced a trend toward reduced resting HR (-2.4%). Integrated CE produced discernibly larger gains than serial CE or a trend for four of six training adaptations. Effect sizes were generally large (60.0% of discernible differences). We conclude that, for cardiovascular and cardiorespiratory adaptations in athletes, strength and endurance training are compatible and that exercise timing and sequence significantly influence training adaptations, complimenting our previous similar conclusions for strength, muscle endurance, body composition, and flexibility.

Concurrent training enhances athletes' strength, muscle endurance, and other measures.

We evaluated the effects of concurrent strength and aerobic endurance training on muscle strength and endurance, body composition, and flexibility in female college athletes and compared two concurrent exercise (CE) protocols. Twenty-eight women (mean age, 19.6 years) were divided into two matched groups and evaluated before and after a vigorous, 11-week, 3-days per week CE training program. One group did serial CE consisting of a warm-up, resistance exercises at low heart rate (HR), aerobics, and a range of motion cool down. The other group did integrated CE consisting of aerobics, the same resistance exercises at high HR achieved by cardioacceleration before each set, and the same range of motion cool down. The two protocols were balanced, differing only in the timing and sequence of exercises. Serial CE produced discernible (p < 0.05) increases in lower- (17.2%) and upper- (19.0%) body muscle strength and fat-free mass (FFM) (1.8%) and trends toward greater lower-body muscle endurance (18.2%) and reduced upper-body flexibility (-160.4%). Integrated CE produced discernible increases in lower- (23.3%) and upper- (17.8%) body muscle strength, lower-body muscle endurance (27.8%), FFM (3.3%), and lower-body flexibility (8.4%) and a decline in fat mass (-4.5%) and percent body fat (-5.7%). Integrated CE produced discernibly larger gains than serial CE for six of nine training adaptations. Effect sizes were generally moderate (44.4% of discernible differences) to large (33.3%). We conclude that serial CE produces adaptations greater than those reported in the literature for single-mode (strength) training in athletes, whereas integrated CE produces discernibly greater gains than serial CE. The results suggest synergy rather than interference between concurrent strength and aerobic endurance training, support prescription of CE under defined conditions, establish the importance of exercise timing and sequence for CE program outcomes, and document a highly effective athletic training protocol.

Elimination of delayed-onset muscle soreness by pre-resistance cardioacceleration before each set.

We compared delayed-onset muscle soreness (DOMS) induced by anaerobic resistance exercises with and without aerobic cardioacceleration before each set, under the rationale that elevated heart rate (HR) may increase blood perfusion in muscles to limit eccentric contraction damage and/or speed muscle recovery. In two identical experiments (20 men, 28 women), well-conditioned athletes paired by similar physical condition were assigned randomly to experimental or control groups. HR (independent variable) was recorded with HR monitors. DOMS (dependent variable) was self-reported using Borg's Rating of Perceived Pain scale. After identical pre-training strength testing, mean DOMS in the experimental and control groups was indistinguishable (P > or = 0.19) for musculature employed in eight resistance exercises in both genders, validating the dependent variable. Subjects then trained three times per week for 9 (men) to 11 (women) weeks in a progressive, whole-body, concurrent training protocol. Before each set of resistance exercises, experimental subjects cardioaccelerated briefly (mean HR during resistance training, 63.7% HR reserve), whereas control subjects rested briefly (mean HR, 33.5% HR reserve). Mean DOMS among all muscle groups and workouts was discernibly less in experimental than control groups in men (P = 0.0000019) and women (P = 0.0007); less for each muscle group used in nine resistance exercises in both genders, discernible (P < 0.025) in 15 of 18 comparisons; and less in every workout, discernible (P < 0.05) in 32% (men) and 55% (women) of workouts. Most effect sizes were moderate. In both genders, mean DOMS per workout disappeared by the fourth week of training in experimental but not control groups. Aerobic cardioacceleration immediately before each set of resistance exercises therefore rapidly eliminates DOMS during vigorous progressive resistance training in athletes.